1. Field of the Invention
The present invention relates to a fuel oil flow improver and a fuel oil composition. More specifically, the present invention relates to a fuel oil flow improver which can sufficiently reduce the plugging point or the pour point of fuel oil, which has excellent dispersibility of a wax precipitated from the fuel oil to which the fuel oil flow improver is added, and also relates to a fuel oil composition containing the fuel oil flow improver.
2. Description of the Related Art
Fuel oils such as light diesel oil and heavy oil A contain a wax which is a long chain n-paraffin, and when the oil temperature decreases, such as in winter, problems occur such as the wax precipitating and plugging the filters in the fuel oil line, or congealing such that fluidity is lost, blocking the line. The temperature at which filter described above is plugged is referred to as the cold filter plugging point (CFPP), and the temperature at which fluidity is lost is referred to as the pour point (PP). Normally, a flow improver is used during the winter in order to improve the plugging point and the pour point.
In addition, in fuel oils such as light diesel oil or heavy oil A, a problem also arises in which the wax precipitates within the fuel tank, and the precipitated wax settles on the base of the tank to form a thick, dense wax layer. It is known that when such a problem occurs, the ability of the engine to start is degraded remarkably, and a wax dispersibility modifier is used in order to improve the problem described above.
As a fuel oil flow improver to impart an improvement to the plugging point, an improvement to the pour point described above, and further, to impart excellent wax dispersibility, for example, it is disclosed in Patent Literature 1 that using a reaction product of an amide compound, including active hydrogen within the molecules, and an alkylene oxide, together with another polymeric additive improves the plugging point and the pour point, and increases the wax dispersibility. In addition, it is disclosed in Patent Literature 2 that a condensation reaction product between an aldehyde, a salicylate, and an alkylphenol, or a compound prepared as a salt by reacting the condensation reaction product with an alkylamine is used in order to improve a degradation of the plugging point caused by using a wax dispersibility modifier, an ethylene-vinyl acetate copolymer, and the like together with each other, thereby the degradation in the plugging point is resolved and an excellent wax dispersibility is exhibited. Furthermore, in Patent Literature 3, it is disclosed that a fuel oil additive containing a graft polymer in which an alkyl acrylate is grafted to an ethylene-vinylester copolymer with a vinyl acetate content of less than 3.5 mol % exhibits an improvement in the plugging point as well as the wax dispersibility.
Meanwhile, automobile exhaust gas regulations are becoming stricter globally in order to improve the environmental problems in recent years. Various exhaust gas purification measures are being promoted in relation to such exhaust gas regulations, and attempts are being made to further reduce harmful components present in the exhaust gas such as nitrogen oxide (NOx) and particulate matter (PM).
As one such technological development, a diesel engine with a high pressure fuel injection pump referred to as a “common rail system” is being developed. This is a system in which fuel of extremely high pressure is injected using accurate computer control. In the common rail system, when trace amounts of foreign elements are present within the fuel, there are concerns that errors may occur in the computer control, therefore a fine fuel filter is provided in the fuel supply line. In a case of a vehicle in which a fine fuel filter is provided in the fuel supply line, the performance requirements in relation to fuel at a low temperature become even more demanding than they have been in the past, there are cases in which the improvement effect of the plugging point and the wax dispersibility is insufficient in a fuel oil flow improver of the related art, and there is a demand for a fuel oil flow improver having a higher improvement effect.